Real world, a three-dimensional world, provides human eyes with two images of phase differences, and the parallax required for the three-dimension vision gets formed once the images come into human eyes, whereby the three-dimensional and stereoscopic perception may be produced through the fusion reflection from optic nerve center and visual psychological reaction. Based on this principle, the stereoscopic perception can be obtained when a display device presents two images—a left image and a right image—with phase differences to a left eye and a right eye respectively.
An auto three-dimensional liquid crystal display that is capable of switching between the modes of two dimension and three dimension appeared with the continuous development of three-dimensional display technology, which is referred to as the parallax barrier technology. To realize the technology, a switching liquid crystal screen, a polarizing film and a liquid crystal layer of polymers are needed, and a sequence of vertical stripes perpendicular in the direction of optical rotation are produced with the liquid crystal layer and a layer of the polarizing film. When light goes through the stripes with width of dozens of microns, a vertical thin stripe grating mode, namely “parallax barrier”, gets formed. In the three-dimensional displaying mode, it is the parallax barrier that determines which pixels on the liquid crystal screen to be perceived by which eye. Nontransparent stripes may obstruct the right eye, when the images for the left eye are presented on the liquid crystal screen; similarly, nontransparent stripes may obstruct the left eye when the images for the right eye are presented thereon. Turning off the liquid crystal switch, the display may become an ordinary two-dimensional one.
However, problems still exist in the above mentioned auto three-dimensional liquid crystal display: three-dimensional images can be perceived only if the line connecting both eyes is perpendicular to the direction of the stripes so as to coincide with the principle of parallax barrier, while it is not in conformity with the principle of parallax barrier if the line connecting both eyes is parallel to the direction of the stripes, and the three-dimensional images cannot be obtained in that case.